AMMAN U.S.-backed Syrian forces fought Islamic State militants on Thursday inside the city of Manbij for the first time since they laid siege to the militant stronghold near the Turkish border, a monitor said.

The British-based Observatory for Human Rights said heavy clashes were taking place in western districts of Manbij after the alliance of Kurdish and Arab fighters swept into the city near the Kutab roundabout, almost 2km from the city center.